Buildings can be cooled and heated by selectively recirculating air within the building using a conventional air handling system, or admitting outside air into the building via the air handling system, while removing excess air via an exhaust capacity in the air handling system depending on the difference between outside ambient conditions and a desire to cool, heat, or ventilate the interior space of the building. In air handling systems, fans are typically used to recirculate air throughout the building for heating or cooling. Typical circulation fans in air handling systems are often operated in conjunction with damper devices mounted to or within the air handling systems to divert a source of air from indoors to outdoors.
U.S. Pat. No. 5,065,585 to Wylie (“the 585 patent”) discloses an apparatus for cooling the interior of a building. The apparatus disclosed in the 585 patent includes a movable blade-type damper assembly mounted in a damper housing. A shaft extends between end walls of the damper housing in the 585 patent and supports the movable blade. A motor drives the shaft to adjust the position of the movable blade between two positions. FIG. 2A of the 585 patent illustrates a first position where air flow communication is established in the damper housing between an outside inlet air duct and interior air outlet duct. At the same time, air is directed from an interior return air duct to an outside outlet air duct to relieve a buildup of air pressure inside the building in which the disclosed air handling system is installed. FIG. 2B of the 585 patent illustrates a second position of the movable blade where air flow communication is established in the damper housing between the interior return air duct and the interior air outlet duct. This position allows for recirculation of air flow within the interior of the building.
The apparatus disclosed in the 585 patent suffers certain shortfalls in operation. Generally, the motor that drives the shaft, based on its actual location at the center of the system, is incapable of exerting enough force/pressure to the blade. Based on this lack of pressure, the blade, while it diverts air, is virtually incapable of sealing the flow path made by the blade in either direction. This, therefore, makes the apparatus disclosed in the 585 patent susceptible to leakage based on, among other things, multiple leak paths and inadequate sealing. The movable blade pivoting at its center makes it difficult to seal around the hinge points and along the sides of the blade. There are also height constraints imposed by the single-blade configuration disclosed in the 585 patent that do not allow for installation of the apparatus in certain size restricted areas. Many attics, for example, cannot accommodate the height requirement of such an apparatus for the enclosure and outside air duct that connects to the top of the apparatus. Finally, the apparatus disclosed in the 585 patent is not able to connect to more than one return air duct. Exterior provisions can be made but size, cost and complexity increase.